With recent development of electronics, proposals of small-sized electronic devices intended to be placed in human or animal bodies have been made.
By way of example, National Patent Publication No. 2003-530135 (Patent Literature 1) discloses a monitoring device for monitoring at least one physiological parameter at an attachment site in a body. The monitoring device includes a detector for detecting the parameter, and a transmitter for transmitting data formed by the detector.
In the field of livestock raising or dairy husbandry, placement of an electronic device with a transmitter in the body of an animal and management or identification of individual sample using information from the electronic device have been proposed. By way of example, Japanese Patent Laying-Open No. 6-276877 (Patent Literature 2) discloses an in-vivo type individual piece identification equipment used retained in the rumen or a reticulum of a ruminant. The identification equipment includes a vessel formed of a material not eroded by gastric juice, an integrated circuit housed in the vessel, and an antenna provided inside or outside the vessel. The integrated circuit transmits data (identification code) stored in advance in response to electromagnetic waves generated outside the body of the animal, through a transmission antenna.
U.S. Pat. No. 5,984,875 (Patent Literature 3) discloses a sensor that senses a physiological parameter (such as temperature) of the ruminant and transmits the results of detection. The sensor has such a size and density that allows the sensor to be retained in the rumen or in the reticulum of the ruminant. Data transmitted from the sensor are received by an external receiver.
By way of example, National Patent Publication No. 2008-529631 (Patent Literature 4) discloses a sensing device configured to be easily swallowable by an animal. The sensing device includes a controller, a transmitter and an array of sensor elements. The transmitter is configured to transmit sensor data extracted from an array output.